A British agent left top secret information about covert operations on a bus in South America when she lost her handbag while on assignment.

The drugs liaison officer lost a computer memory stick said to contain a list of undercover agents’ names and details with more than five years of intelligence work.

It happened when the MI6-trained agent left her handbag on a transit coach at El Dorado airport in Bogota, Colombia. Intelligence chiefs were forced to wind up operations and relocate dozens of agents and informants amid fears the device could fall into the hands of drugs barons.

The agent’s employer, the Serious Organised Crime Agency, Saturday confirmed the data loss but said it had happened soon after the agency had been set up in 2006, “while staff were still working to the data-handling policies of precursor agencies.”